Except for DS3 (who still occasionally wets the bed), I have a fake down comforter in a pottery barn duvet for everyone in our house. They keep the duvet and comforter on all year long. In the winter I add a quilt to the foot of their bed that they can pull up over the duvet if they are still cold or I can pull over them as I'm tucking them in. The quilts are pottery barn too.
Down comforters, depending on the quality, shed feathers like crazy. And they create a lot more dust in the room too. If someone in your family has allergies down comforters can exacerbate them. Also, some wash up well, some need to be dry cleaned. And if there is a tiny hole in the comforter, it can stretch when being washed or dry cleaned and can leak out feathers into your washing machine. I used to work at a dry cleaners and cleaning down comforters and down mattresses was always a gamble. We hated doing them.
eta: whether you get synthetic or real down, I highly recommend Company Store comforters. They also have the tabs for tying the comforter to the duvet.
" I object to violence because when it appears to do good, the good is only temporary; the evil it does is permanent." Mahatma Gandhi
"This is the ultimate weakness of violence: It multiplies evil and violence in the universe. It doesn't solve any problems." Martin Luther King, Jr.